One way I overcame this issue by creating a helper that translates (1,2,3,4,5....) into OR statements on the fly (in the data layer of my app). So
select * from customers where customer_id in (1,2,3,4,5)
Surprisingly there is not much of a penalty performance and the where string can be quite long. I managed to build a where clause with 100 or so OR statements in it.
select * from customers where customer_id = 1 or customer_id = 2 or customer_id = 3 or customer_id = 4 or customer_id = 5
Btw, are you trying to overcome the issue of missing inner joins with this?